Various manufacturing techniques have been devised to make swelling packers of the type that extend for a substantial length of a tubular. One such method is discussed in detail in U.S. Pat. No. 7,478,679 and shown in FIG. 5. It uses a sleeve 10 that is slipped over a tubular mandrel 12 that is typically a stand of a tubular string. The tubular string except for the mandrel is not shown. A mold is placed over the tubular leaving space at opposed ends to inject epoxy that can then set up and become end rings 14 and 16. Metal end rings can instead be spot welded.
This is meant as a design that can be field assembled. It uses a seamless sleeve that has to be fed over the end of the pipe and presents certain logistical issues in handling of the pipe and the sleeve to get the sleeve 10 on the pipe 12 quickly and without damage followed by having to pick up the stand of pipe and make it up to the string in a manner that will not damage the element 10.
Another technique of assembly of swelling packers is illustrated in US Publication 2008/0210418 that is discussed below in conjunction with FIGS. 1-4. FIG. 2 shows a mandrel 20 used for the construction technique while FIG. 3 shows one of two similar jacket halves 22 that are generally metal sheet rolled at 24 to a diameter somewhat larger than the intended outside diameter of the mandrel 20. A series of aligned elongated slots 26 are put there to allow the rubber to better retain the halves 22 when the two of them are mounted over the mandrel 20 after an initial layer of the swelling material 28 is built up on the mandrel 20. Each of the halves 22 has a series of spaced rounded end loops 30 through which a rod 32 is inserted before the now connected halves 22 are applied to the first layer of swelling material 28. Located at the opposite end from loops 30 are loops 34 that are somewhat rectangular shaped and that will ultimately accept a pin 36 that has the same general shape as the loops 34 and gets narrower toward its lower end 38. A dummy pin is inserted into loops 34 during the rubber wrapping process and curing or vulcanization cycle to keep the rubber out of them. During the vulcanization cycle, the outer layer of swelling material 28 is fully bonded to the halves 22 and the inner swelling layer. The dummy pin is pulled out of loops 34 and a lengthwise undulating seam 40 is cut through the swelling material in the gap between the halves 22 that has opened up when the dummy pin (not shown) was pulled out. There now is an open seam in the swelling element 28 that allows it to be slipped over any similar size mandrel or tubular string like 20. Once the assembly is over the mandrel 20 the loops 34 are again lined up or pulled into alignment by insertion of the pin 36 into an end loop and driving the pin 36. Once a few loops are temporarily held in alignment to insert the pin 36, the wedge shape of the pin 36 brings the remaining loops 34 into alignment as the pin 36 advances. The intent is to have the pin 36 wedge in the loops 34 so that it stays put when the assembly is run into the well and the element 28 swells to seal the wellbore.
While the above described technique accomplishes the intended task it requires size specific inventory of the halves 22 and has a few inherent complexities in the many steps of the manufacturing process to get the halves secured to each other and temporarily secured around the layup layer of the swelling material while more swelling material is applied. Additionally, the act of removal of the temporary pin from loops 34 and making the longitudinal seam 40 without damage to the loops 34 can also be a challenge. Finally, getting the loops 34 initially aligned so that a very long pin 36 can be driven through the loops to close the seam 40 tightly can also present assembly challenges.
The present invention targets some of the difficulties in the designs discussed above and presents a method and a resulting product that is simpler to assemble and deploy in the field and allows for use of a parts inventory that has fewer discrete parts to handle a broad range of sizes. It encompasses using split rings that can be embedded totally or partially coupled with using magnetic pulse welding and/or crimping techniques to adhere the split ring ends to each other and/or the underlying mandrel. By closing a longitudinal seam in the swelling material in this manner, the seam is better sealed and the assembly goes together faster with greater assurance that it will remain intact as the assembly is run downhole and the sealing element swells. The split rings are economical to field fabricate to the approximate desired material reducing the need for unique inventory and again making field assembly simpler even with minimally trained personnel. In an alternative embodiment the ends can overlay the swelling element and be joined by magnetic pulse welding or crimping techniques such as those offered by Pulsar Ltd. of Raanana, Israel and whose magnetic pulse welding technique is described at http://www.pulsar.co.il/technology/?did=16.
U.S. Pat. No. 6,779,550 illustrates magnetic pulse welding techniques to make a pressurized canister.
Those skilled in the art will appreciate other aspects of the invention from a review of the preferred embodiment description and associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.